In certain situations, in particular for producing device parts comprising germanium, methods are resorted to wherein germanium forms the subject of an epitaxial growth based on a portion of semi-conductive materials, generally silicon.
It is in this context, that the document Yamamoto et al. [Yamamoto et al. ECS Journal of Solid State Science and Technology 3, 353, 2014] discloses a germanium growth based on a silicon on insulator type substrate, also called SOI. According to this document, illustrated by FIGS. 1 and 2 of the present application, firstly producing silicon dioxide patterns in the form of tiles 4 spaced apart from one another above the SOI stack; this type of stack comprises a base layer 1, generally silicon, a buried insulating layer 2, generally of silicon dioxide and a superficial silicon layer 3 being used for the later construction of other parts of the device. An example of tiles 4 corresponding to FIG. 1a of this publication is given in FIG. 1. An etching of the superficial silicon will be proceeded with, making it possible to expose the buried layer in the zone 21 around the tiles 4 and to partially attack the superficial silicon layer below the tiles 4. This lateral attack is visible in FIG. 2. It makes it possible to release a volume confined between the upper surface of the buried layer 2, the lower surface of the tiles 4 and the side wall of the superficial residual layer 3. This volume then forms the subject of a filling with germanium 5 by lateral growth on the silicon wall of the cavity. This scientific publication further outlines that the defects, schematised in the reference 6 in FIG. 2, can be observed in germanium coming from the growth, in particular in the proximity of the interface with the silicon. FIGS. 3 and 4 show the defects that can thus be encountered during the growth of germanium, with the planar defects and orientation problems. In the conclusion thereof, Yamamoto et al. indicate that the parts having defects can be removed later by an additional lithography followed by an etching process. It emerges that this method leads to numerous steps without guaranteeing the quality of the portion ultimately produced from germanium.
It is an aim of the invention, to overcome at least partially the disadvantages of the current techniques, in particular by proposing an improved method.